Playing with universality classes of Barkhausen avalanches

TL;DR

This paper investigates the universality classes of Barkhausen avalanches in ferromagnetic films, revealing how material structure and thickness influence avalanche statistics and demonstrating a dimensional crossover in domain wall dynamics.

Contribution

It provides the first experimental evidence of dimensional crossover in Barkhausen avalanches and links material properties to universality classes in ferromagnetic films.

Findings

Scaling exponents vary with material structure and thickness.

Quantitative agreement with theoretical models of domain wall dynamics.

Identification of a dimensional crossover in avalanche behavior.

Abstract

Many systems crackle, from earthquakes and financial market to Barkhausen effect in ferromagnetic materials. Despite the diversity in essence, the noise emitted in these dynamical systems consists of avalanche-like events with broad range of sizes and durations, characterized by power-law avalanche distributions and typical average avalanche shape that are signatures dependent on the universality class of the underlying dynamics. Here we focus on the crackling noise in ferromagnets and scrutinize the traditional statistics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films having different thicknesses. We show how scaling exponents and average shape of the avalanches evolve with the structural character of the materials and film thickness. We find quantitative agreement between experiment and theoretical predictions of models for the magnetic domain wall dynamics, and then elucidate the universality classes of Barkhausen avalanches in ferromagnetic films. Thereby, we observe for the first time the dimensional crossover in the domain wall dynamics, and the outcomes of the interplay between system dimensionality and range of interactions governing the domain wall dynamics on Barkhausen avalanches.